I suggest you take your bow to the shop and let them measure your drawlenght. They have special arrows to do that. Get the bow fitted to your correct lenght and get the poundage down to 50-55 lbs. Then take your gear and join an archery club. Most can give you assistence with the correct stance, shooting errors, etc. They can also help you finetune your bow.
Then start to practice, practice and practice.
Bowhunting is beeing a good hunter, but also a good archer.
In the shooting range you have perfect conditions to sight in your bow so when you take it to the woods you are certain the bow isn't the problem.
Even more then gunhunting bowhunting needs very wellcontroled and performed movements.
Without a good basis you might see a lot of deer, but will get frustrated because you might not harvest them due to bad form and wrong set up.